Lord Heywood of Whitehall - more familiarly known to us as Sir Jeremy Heywood - served four Prime Ministers in No 10 with great distinction. His early death at the age of 56 robs the country of a very able public servant at a defining moment in its modern history.

I met Sir Jeremy as part of my professional work. He had prioritised improving the civil service’s commercial capability as one of his top three action points on becoming Cabinet Secretary. He showed an openness and willingness to engage on the issues rare amongst his senior civil service or Ministerial colleagues. One day I received a DM on twitter from his account. Assuming this showed his account had been hacked I telephoned his office to alert them. After checking with him I was informed by his office it was indeed Sir Jeremy himself checking up on the progress of talks with his officials. It was an impressive personal display of the grasp of detail he was noted for by all those who worked with him.

As Cabinet Secretary Jeremy Heywood ensured the smooth running of David Cameron’s government and implemented a smooth handover to Theresa May’s administration. Earlier he was called back from his job in the City, where he had moved after a stint working for Tony Blair, to try and sort out the shambles that was the hallmark of Gordon Brown’s tenure as Prime Minister.

He was initially a reluctant Head of the Civil Service. The splitting of the roles with Bob Kerslake however was not a success and he assumed the additional role with gusto. He was a doughty defender of the Service whilst being realistic about where it needed to modernise.

At first hand I witnessed the strength of his character and his determination to do a professional job as a civil servant. He knew and understood the responsibility of government and he knew and understood the responsibility of the job of a civil servant to do the work of the politicians elected to govern.

Jeremy Heywood was unstuffy and seemingly unflappable. He was easy to do business with because he had an immense grasp of the detail at hand and brought a dispassionate commitment to finding the best solution available. Characteristics that were invaluable to the Prime Ministers who relied on him and the country he served with such enormous integrity and professionalism.